Allosteric activation of an ion channel triggered by modification of mechanosensitive nano-pockets
Allosteric activation of an ion channel triggered by modification of mechanosensitive nano-pockets
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DOI：
10.1038/s41467-019-12591-x
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发表时间：
2019-10-10
影响因子：
16.6
通讯作者：
Pliotas, Christos
中科院分区：
文献类型：
--
作者：
Kapsalis, Charalampos;Wang, Bolin;Pliotas, Christos
离子通道的跨膜纳米袋内的脂质可用性与机械感觉有关。然而，阻碍脂质链渗透到纳米口袋中对通道结构的影响尚未得到证实。在这里，我们确定大电导机械敏感通道MscL，高压阈值通道上的纳米口袋。我们通过诱变和巯基修饰限制脂质链进入纳米口袋，并通过PELDOR/DEER光谱监测通道构象。对于位于纳米袋入口处和通道孔远端的单个位点，我们在不存在张力的情况下产生变构响应。单通道记录揭示了一个显着降低的压力激活阈值的修改后的通道和子传导状态的情况下施加的张力。巯基修饰减少后，阈值恢复至野生型水平。与构象变化相关的修饰限制脂质进入纳米袋，中断膜和介导机械敏感性的通道之间的接触。
Lipid availability within transmembrane nano-pockets of ion channels is linked with mechanosensation. However, the effect of hindering lipid-chain penetration into nano-pockets on channel structure has not been demonstrated. Here we identify nano-pockets on the large conductance mechanosensitive channel MscL, the high-pressure threshold channel. We restrict lipid-chain access to the nano-pockets by mutagenesis and sulfhydryl modification, and monitor channel conformation by PELDOR/DEER spectroscopy. For a single site located at the entrance of the nano-pockets and distal to the channel pore we generate an allosteric response in the absence of tension. Single-channel recordings reveal a significant decrease in the pressure activation threshold of the modified channel and a sub-conducting state in the absence of applied tension. Threshold is restored to wild-type levels upon reduction of the sulfhydryl modification. The modification associated with the conformational change restricts lipid access to the nano-pocket, interrupting the contact between the membrane and the channel that mediates mechanosensitivity.